Regular black holes and black universes

TL;DR

This paper explores regular black holes called black universes, which replace singularities with expanding cosmological regions, potentially allowing observers to survive inside such black holes, and discusses their theoretical foundations and implications.

Contribution

It introduces the concept of black universes with Schwarzschild-like structure and expands on their theoretical construction using phantom matter, offering new insights into non-singular black hole models.

Findings

Black universes have an expanding interior instead of a singularity.

Solutions are obtained with phantom matter distributions.

A specific positive-mass black-universe solution is provided.

Abstract

We give a comparative description of different types of regular static, spherically symmetric black holes (BHs) and discuss in more detail their particular type, which we suggest to call black universes. The latter have a Schwarzschild-like causal structure, but inside the horizon there is an expanding Kantowski-Sachs universe and a de Sitter infinity instead of a singularity. Thus a hypothetic BH explorer gets a chance to survive. Solutions of this kind are naturally obtained if one considers static, spherically symmetric distributions of various (but not all) kinds of phantom matter whose existence is favoured by cosmological observations. It also looks possible that our Universe has originated from phantom-dominated collapse in another universe and underwent isotropization after crossing the horizon. An explicit example of a black-universe solution with positive Schwarzschild mass is discussed.